Described herein are aspects generally related to communication systems, and more particularly, to transmitting hybrid automatic repeat/request (HARQ) communications in communication systems.
Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power). These multiple access technologies have been adopted in various telecommunications standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level.
An example of a telecommunications standard is Long Term Evolution (LTE). LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by Third Generation Partnership Project (3GPP). It is designed to better support mobile broadband Internet access by improving spectral efficiency, lower costs, improve services, make use of new spectrum, and better integrate with other open standards using OFDMA on the downlink (DL), SC-FDMA on the uplink (UL), and multiple-input multiple-output (MIMO) antenna technology.
In wireless communications systems employing LTE, a user equipment (UE) served by one or more evolved Node Bs (eNBs) can communicate using HARQ communications. The HARQ communications may indicate to the UE whether communications are received, and accordingly the UE can schedule retransmission of communications that are not received.
With development of lower latency communications, a shorter transmission time interval (TTI) (e.g., a TTI less than the 1 millisecond TTI of LTE) is supported. In addition, high reliability low latency (HRLL) communications are being developed for “mission critical” applications, which demand very low error rates (e.g., 1e-4 or less) along with the low round trip times (e.g., 500 microsecond or less) characteristic of the lower latency communications. Enhancements to current HARQ mechanisms may be needed to support the high levels of reliability demanded by the mission critical applications along with the low latency of HRLL communications.